Thermoplastic (non-thermoset) epoxy resins have been employed in the formulation of highway pavement marking paints as disclosed by J. M. Dale in "Development of Lane Delineation With Improved Durability", Report No. FHWA-RD-75-70, July 1975, available from U.S. Dept. of Trans. Off. of Dev., Federal Hwy. Admn., Wash. D.C., 20590. The paint formulations are maintained at elevated temperatures, usually 450.degree. F. to 500.degree. F., during application. While they provide an excellent highway marking paint in terms of abrasive resistance, they are deficient in terms of applicability since they exhibit a substantial increase in viscosity while being maintained at the application temperature.
It would be desirable to have a thermoplastic (non-thermoset) epoxy resin which exhibits a much reduced viscosity increase at elevated temperatures, i.e. it is more thermally stable than those thermoplastic epoxy resins disclosed by J. M. Dale. It is desirable that the increase in viscosity at 450.degree. F. (232.degree. C.) after being subjected to a temperature of 450.degree. F. (232.degree. C.) for 4 hours be not greater than about 10% above the initial viscosity at 450.degree. F. (232.degree. C.).